The present invention relates to a hood for an endoscope which is mounted on a distal end portion of an insertion section of the endoscope.
In the observation and surgical operation of the body cavity of a patient using direct-viewing type endoscope, an observation space and operation field have to be secured with an endoscope's hood attached to the distal end portion of an insertion section of the endoscope when the observation space and operation field in particular are narrower in a location such as the esophagus and duodinal bulb.
In a location, such as the stomach, where a broader observation space and operation field can be secured, the endoscope's hood attached to the distal end portion of the insertion section of the endoscope shades or blocks the observation space and operation field and it is difficult to perform proper procedure due to the presence of such a hood. It may be considered that, in such a case, a hood need be removed from the endoscope. At that time, the endoscope's hood has to be withdrawn out of the body cavity and removed from the endoscope, thus involving a cumbersome operation and more operation time. This gives an excessive burden to the operator and to the patient.
As shown in JPN UM APPLN KOKAI PUBLICATION NO. 55-19682, a hood unit has been proposed comprising a hood slidably mounted on the distal end portion of the insertion section of the endoscope, a spring means for urging the hood in an extending direction, a retaining mechanism for retaining the hood in a retracted position against the action of the spring means, and a string-like wire for releasing the retainment of the hood by the retaining mechanism, whereby the visual angle can be changed by moving the hood. Such a slidable system requires a mechanism for slidably moving the hood, a mechanism for retaining the hood in a retracted position, a retainment-releasing operation mechanism, etc., thus complicating the structure at a distal end portion of the endoscope.
JPN PAT APPLN KOKAI PUBLICATION NO. 9-66019 has proposed an endoscope having a hood at a distal end portion of an insertion section and a high-frequency snare wire anchored to the outer peripheral portion of the hood. The endoscope's hood in this case is fixedly mounted on the distal end portion of the insertion section. For this reason, the visual field is shaded at all times by a projected hood, thus lowering the observation capability.